Viscometer



Oct. 25, 1960 H. T. KENNEDY irAL 2,957,338

- vIscoMETrzR l Filed Nov. 29, 1957 4 sheets-snm 2 N *NN N 'l a QQ N Ill n T `T I f /f /f I ts N N n [lll 5y' @QJ 1% am Filed Nov. 29, 1957 l FIEL? H. T.`KENNEDY EI'AL vIscoMETER l v4 Sheets-Sheet 4 This invention .relates..-.to a device lfor .measuring the viscosity ,of fluids.-. More .particular-ly, this invention relates v.toa .device yfor. lmeasuringuthe viscosity of. fluids at. diiferent pressures and tempera-tures, and is particularlyadaptable .to measuringthe .viscosityvor changesin viscosity ,of fluids 4.which undergo. a. chemical. or physical reaction o-f change. depending in part upon-.the pressure andvgtemperaturenof vthe :uidu

Whileiourinventionisnot. so limited-it is particularlyv well adapted for. measuring `the Viscosityof Huid materials commonly used :inthe oilland gas industry. In .-connection with'thedrillingpf wells, atvariety of fluid. compositions. are subjectedto. elevatedpressures andtemperatures which occassionallyause rapid increasesinthe viscosity ofV suchlfluid compositions which are pumped into thewell bores.

In the .completionof .oil and gas-wells, itiscommon.

practice-to pumpcacementic'eous slurry down-into the well throughfcasing-and .force this slurryuplhrough the annulus .between,|the..casing and the Iwellvvbore. This operationis -designedfto Yseal V oifithe. overlying earth formations fromttheil or gas producing zonetwith set cementn Itisvconmionknowledge that a s`lurry.of vPortlandcement, with=oriwithout` aggregates or other additives contained therein, tends-.to thickenand [occasionally fla-shlset. in .the .-welllin'a .relatively short period of` time.. The. deeper=` the well,.the higher-willbe the temperature tand. pressure. to.whioh .the ,cement slurryf is subjected and .theseconditionsaggravate the settingproblem.

In. view.ofithe.foregoingfacts there has been a great needn-for. yapparatus...which. is.. capable of. lmeasuring y the changeqin viscosity ofPortland cement slurries and other fluids which will be subjectedtohigh.temperature ,andi

pressure conditions inwells.... Theseconditionsmay,vary from .a..thousand.. tothree y.thousand :lbs/sq. vinch and from..l to..25.091F.,.although,in very .deep wells even` more isevere .conditions fare .frequently encountered.V

Certainforms ofapparatus. have been -devisedsby others to measure fthe. changes -inffviscosity t of Portland Vcement.v

slurries.under-.controlled time-pressure-.temperatur/e.,conditions. physically-quite cumbersome... To the bestof our..knowl edge, there are-nosuchs devices-:that are readilyv transportable:4 into the-oil fields.- They-are normally retained in regional--tlaboratoriesfwherewiscosity tests,.are made.

It is;y however, desirablef-.tohave#` a.- portable`v viscometer t' whichfcan achieve the:aforementioned'results and-which can be-used' on l.the-well -sitezfto` measure. theviscosity ofV cement 'slurriessamples-taken wdirectly. lfrom-,cement trucks i just priortothe pumping, ofthecementfslurryinto -.thewell for. cementingeasing.

The devices which have heretofore beenx-usedzforfthe-1v aboveffstatedrpurpesesf-areffuither provided Withfpaddles,

agitators or-=fsimilarm means whichV continuously stir` the@ cementfrs-lurry 'or otherwwelly fluid .in the testingvapparatus over afdesired time-pressure-temperature testing cycle;

When@ friable imaterialslg. such i as lightweight r aggregates These devicesz-are, however; very expensive andu ice used forwsealing orbridging Voff certain areas in. thefsubterranean formation are incorporated into the cement slurry,-these internal mixing devices tend to degrade or abrade such materials and this will have an effect upon the viscosity andsetting time ofthe cement slurry. Therefore,` the conventional laboratory devices currently in use cannot give a ltruly accurate prediction of the viscosity changes of the cement-aggregate'slnrryunder actual well conditions.

Ourv invention-is :also adaptable for the study of changes in viscosity of oil wellY drilling uids under varying conditions of pressure Vand'temperature. It is also useful in the testing ofuid compositions whichr are not necessarily connected `to2/the 'drilling and completion of oilfand gas wells'.- For example, 4our device 'can be used in measuring the-viscosityfof lubricants, whether these be of petroleum base or some other base material, liquid` food stuffs such'as -syrups,=-molasses; anti-freeze solutions, etc. Ourfdevicefis.further'adaptabie to measuring the viscosity of such materials at temperatures and pressures eitherabove or .belowfusually prevailing atmospheric con- Y ditions.

It is an-object of our inventionto provide an apparatus for measuringuthe viscosity of fuids at -hig'h for low' pres- 1 sures andrf.temperatures.- Another object is -to provide an improved apparatus for continuously measuring the viscosity; of 'uids :under the rpreviously stated-.conditions.

ing, any ,timeintervah of yfluids which-are characterized by undergoing chemicals or physical reaction or change,

dependingupon `conditions of time, pressure, and .tem-

perature Itis :a further object of ourlfinventionwto provide adevicefor-.measuring the ,viscosity of uids lwhich contain-i-friable 4materials suspended thereinV in which the.- degrading-of such? materials is :minimizedor substantially eliminated.;

Further :objects .1 and 1 advantages lof our invention will beapparentfromthe'following detailed description `when 1 considered in conjunction with the accompanying draw-V Figure-l ris a perspective view of our viscometer, with certain lfeatures of.the-invention shown in cross section, and certainfeatures being represented schematically or diagrammatically.

Figure-2 is aperspectiveviewA of a modied viscometerof the present invention, also.with certain features shown in cross section.

Figures 3, 4 and 5 are different views of the'interrupter f orftimer-mechanism` designated generally as` 4 in Figure l.

Figure v6is asschematc viewof an' electrical circuit which is-employed-in conjunction with the viscorneter/ shown `in -Figure' l.

Figure-7 `is-ar schematic view yof an electrical circuitVY which -isemployed lin conjunction with the viscometerI shown in Figure 2.

lnl a Ibroadjembodiment our invention comprises a; device for `measuring t-he` viscosity of a uidcomprising in combination a 4resiliently 'mounted-.or supported nonmagnetic containerfor the iluid, means .for establishing a magnetic fleldfin adened area.or `portionofsaid container, meansnesponsive `to said-magnetic field-.positionedv withinzsaid container and freely. `movablein the Huid, and means for measuring the movement of the container when a magnetic field is established.

Referring now to the drawings, there is shown in Fig-r ure-fl, onewspecitictembodiment.of our. viscometer. which comprisesfawbasewmember. or-panelr17 `which can be ofsteel, wood or other construction. Pivotally mountedl on the base 17 is afsuppprt member which, in the preferred Patented Oct: 25, 196) It is afurthe-robject of `'our invention to `provide an apparatus forfmeasuringythe viscosity, atany,particular'tirne or dur- Y embodiment -illustrated in the drawing, consists of a torsion bar 12 and movable support arm 5. The torsion bar 12 and support arm 5 are in a plane substantially parallel with the base y17 and are supported above the base by means of torsion bar support member 18 which in turn is xed .to the base \17 by means of a clamp 19 secured by fastening bolts 19a. Additionally, the torsion bar 12 is supported on the base 17 by means of a pivot support member 12a adjacent to the point where the support arm and torsion bar 12 are joined. Vertically mounted on the support arm 5 is a container or pressure vessel 2 having an interior sample chamber 21 and is preferably provided with suitable exterior insulation 9. In a medial portion of the container is provided a means for establishing a magnetic eld such as a solenoid winding 3. The container 2 is constructed of non-magnetic material, i.e. material which will not substantially interfere with the transmission of magnetic ux. The stop of the container 2 is provided with a closure 2a which will hold any predetermined pressure within the container.

Inside the container 2 is placed means responsive to the magnetic eld established by the solenoid, such as a core 1 which will have an appreciable viscous drag when it rises and falls in the fluid. Preferably, core 1 consists of a cylinder of soft iron with a rounded point at each end, but it should be understood that the invention is not limited to this particular armature configuration. The core 1 is freely positioned in the sample chamber 21 and can move up and down inside the container in response to the lifting action of the solenoid 3 when the latter is electrically energized. As shown in Figure 6, the solenoid 3 is periodically actuated by an electric current by means of an interrupter 4, the details of which are shown in Figures 3, 4 and 5 and which are hereinafter described, A conventional clock motor mechanism 20 (shown schematically) drives the recording drum 7 on which is placed suitable recording chart paper 7a. In contact with the movable support arm 5 is a recording arm 6 which is pivotally supported from the base 17 by means of recording arm pivot support 6a. Attached to the end of recording arm 6 is a pen stylus 6b which is maintained in contact with the chart 7a on the clock-actuated recording drum 7.

In the event that it is desired to use the viscometer of our invention for measuring viscosities at elevated or reduced temperatures or pressures, our device is equipped with a heating coil 8, and a fluid-transmitting coil 1'1 which communicates with the sample chamber 21 of the container 2 through 4the cap pressure closure 2a by means of sealing member 2b and a channel 2c. The coil 11 is secured to the base 17 by means of a clamp 8a and clamp support 8b. A pump (not shown) is connected to coil 11 through valve 15, and there is further provided a pressure gauge 13 to measure either positive or negative pressures in the sample chamber 21. Additionally, the container 2 is provided with means for measuring the temperature of the uid in sample chamber 21, for example, a thermometer well 14 in which, preferably, a bi-metallic thermometer is employed and which is connected to a recorder (not shown) to measure the temperature of the fluid sample at any given time or over a given time interval. In order to supply energy to heating coil 8 there is shown a transformer knob l10a for a conventional variable transformer (shown in Figure 6) and fixed to the base 17 by means of support member 16, the latter also serving to support the clock motor mechanism 20, recording drum 7 and solenoid circuit finterrupter 4.

Also in Figure l, when lfluids of diierent densities are to be placed in sample chamber 21, the recording arm 6 will assume different positions on the chart 7a and might even conceivable cause the stylus 6b to go off the deflection recording chart 7a. This problem is solved by adjusting the exible support mem-ber, consisting Q tOISOll bal" 4 12 and support arm 5, so that the stylus 6b will be set at a predetermined zero position, by means of the clamping arrangement 18a and 19; or alternatively, by adjusting the recording arm support 6a.

In operation, our invention measures -the variation in the viscosity or stiffness of the fluid in sample container 21 with time, under any predetermined schedule of pressure and/or temperature. The sample container 21 is lilled with the uid under test, such as a Portland cement slurry with an aggregate suspended therein which is to be used in cementing casing in a well bore. The transformer knob A10a is set at a position so that the temperature of the sample will be raised to a desired point. If desired, uid is pumped through valve 1S and the coil 11 into the sample chamber to give any desired pressure. The torsion bar 12 is adjusted by turning torsion bar support member 18 and 18a in the clamp 19` so that vthe stylus 6b on the recording arm 6 will bev placed at a zero setting, preferably in the center of the chart 7a. The clock motor 20 which actuates the recording drum 7, and the interrupter 4, driven by interrupter motor 32 (Figure 6), are then started. The cycles or speeds of these two motors are suitably synchronized. A convenient rate for the interrupter is about l cycle every 5 seconds, but obviously this may be varied as desired. When the solenoid winding 3 is periodically electrically energized by interrupter 4 a magnetic eld is established in a defined, usually medial area of the vessel 2. This causes the core 1 to be accelerated from the bottom of the vessel into the magnetic field. Correspondingly, the resiliently mounted container 2 is drawn downwardly towards the upwardly rising core, thereby establishing an unbalanced reaction against the exible, resilient support member 5. The downward movement of support arm 5 will cause the end of the recording arm 6 which carries the stylus 6b to move upwardly and make an appropriate lined record on the chart 7a on the moving recording drum 7. When the interrupter 4 deenergizes the solenoid 3, the support arm 5, recording arm `6 and stylus 6b will return to their normal position or zero setting. As the interrupter 4 intermittently electrically energizes the solenoid 3, the support arm 5 will deect downwardly and the recording arm 6 will deect upwardly. The magnitude of the upward deflection of arm 6 is recorded by stylus 6b and will be an inverse function of the resistance to ow of the uid surrounding core 1. There will, of course, be a correspondingly downward deflection of recording arm 6 caused by the deacceleration of the core `1 on returning to its normal position in the container 2 when the solenoid is deenergized by the interrupter 4.

The record thus obtained shows the viscosity or resistance to ow of the fluid at any given time, and the chart deflection lines on the chart can be calibrated in any desired units. When the fluid in sample chamber 21 becomes stit enough to prevent the movement of core 1 when the solenoid 3 is electrically energized, there will be no deflection of recording arm 6 and the record on the chart 7a will show a horizontal straight line.

The term resiliently mounted when used herein and in the appended claims in connection with the uid container is deemed to include supports other than the one described in the preceding specific embodiment and as further exemplified by the drawing of Figure l. Other supports or mountings for the container may be used provided that they are movable in an upward-downward motion, or are similarly elastic or compressible, and other means may be employed for recording such movement, the latter means being either electrical, mechanical, or electromagnetic.

For example, in place of the support member consisting of torsion bar 12 and support arm 5 of Figure 1, we can use other resilient, i.e. elastic and/or compressible mountings and in connection therewith, means other than the recording arm 6 and pin stylus 6b may be used for insenese n dicating or recordingth'e movement of such-fsupports ork mountingsiwhen the container 2-is moved upon energizing the solenoid 3 andV in response to the movement of the core 1. Therefore, we Vcontemplate asv being .withinl the scope of our invention the use 'of an electrical transducer, such as a carbon pile, upon Which-the' container 2 is mounted or supported, such-a transducer is shown schematically in Figure 2. In principle, such transducerv consists of a conductor 22, which may be a series or plurality of plates"34,"`as"exemplid" in a carbon pile, through which is impressed or paSseda constant voltage. Connected tothe transducer by either'electrical or electromechanicall means is a meter 35 Figure"7) or recording chart which indicates the current being passed through the transducer atiany given Vtime. Whenthe container 2 containingstheifluid Whose viscosity is to bevmeasuredfis placed upon the transducer 22;; and a constantvoltage (such as from powerrlines 25 and 26, through switches 27 and 33 of Figure 7), is impressed across the transducer,A

the electrical current will vary' measurably when the solenoid coil 3 is periodically energized and the core 1 is accelerated into the magnetic field. The resistance across the transducer is directly proportional to the acceleration and deceleration of the core 1 when the latter is moving through the fluid, and this resistance may be measured by recording with meter 3S the current fiowing through the transducer. When there is no motion of the core 1, i.e. when the viscosity of the fluid has reached a maximum and prevents movement of the core, the electrical current record will be a straight line such as is produced under similar conditions in the case of the embodiment shown in Figure l. A suitable carbon pile transducer is described in Catalog J200 published in 1958 by the Central Scientific Company, Chicago, Illinois, at page 234, Catalog No. 82905.

The electrical circuits of Figures 6 and 7 employed in conjunction with the devices exemplified in Figures 1 and 2 have already been partially described in some detail. Numbers in these figures which are common with numbers of Figures 1 or 2 are, of course, for the same elements. In addition, 25 and 26 are power lines normally carrying 110 volts, 60 cycle alternating current; the transducer is made up of carbon plates 34; 27, 28, 39, 30 and 31 are switches to energize the main circuit, the clock motor 20, the transformer 10 for the heater i8, the interrupter motor 32 and the solenoid coil 3, respectively; 33 is a switch to energize the transducer 22 and 35 is a meter to measure the current flowing through the carbon plates 34 of the transducer.

The interrupter 4 is a conventional timing device for periodically and regularly energizing solenoid 3. It is shown in detail in Figures 3, 4 and 5 in order that its utilization in the present setting may be clearly understood. The interrupter 4 is actually an adjustable split cam which is driven by an electric motor 32 at a pre-determined rate. As the cam 4 revolves, it exerts a tension against spring arm roller 23 during part of its cycle, causing the contacts of microswitch 24 to close and energize the solenoid for the desired period of time, depending on the rate of revolution and the settings of the cam. The interrupter unit may conveniently be mounted on support member 16. A suitable 60 cycle, 115 volt device is manufactured and sold by Herbach & Rademan, Inc., Philadelphia, Pennsylvania, and is illustrated on page 7 of their catalog for March-April 1956, under Catalog No. HR-009.

Valve is supplied by the American Instrument Company. 'Ihe transformer 10 is a Powerstat Type 116, 120 c.p.s. (0 to 140 output voltage) unit manufactured by the Superior Electric Company, Bristol, Connecticut. Suitable clock motors and recorders are described in Instruments for Measurement and Control, by W. G. Holzbock, Reinhold Publishing Corporation (1955), page 51, and in the February 15, 1958, parts manual for recording charts published by Minneapolis-Honeywell, page PLIS- 078.

In place ofthe heating-coil 58 shown in Figuresl andi, a'cooling` coil may be substituted through vwhich is passedwater, or a'fluidor gaseous refrigerant.

While we -haverdrescribed our inventionin connection` with certain specific embodiments thereof showingcertainconvenient features vand equipment,'we vdo-not'wishfto lim-it ourselves to such specic features but only-bythe scope of y the1 following claims.A

lWe clain:

ing a magnetic eld in a portion of said container, means having an appreciable viscous drag land being responsiveto said field positioned within said container and freely movable in the Ifluid, and means for measuring the movement'of the container when a magnetic field 'is established. 2. A devicefor measuring-the viscosity of "a-fluid com-` prisingin combination a resiliently mounted substantially` non-magnetic container for the duid, a solenoid Winding surrounding a medial portion of said container, a solenoid core positioned and freely movable in the fluid Within said container, means for intermittently electrically energizing said winding whereby said core is caused to move into the resultant magnetic field, and means for measuring the movement of the container caused by the action of said field upon said -core when the solenoid is energized and the core moves through the fluid into said eld.

3. A device for measuring -the viscosity of a iiuid cornprising in combination a substantially non-magnetic container mounted on a resilient support member, means for intermittently establishing a magnetic eld in a medial portion of said container, means having an appreciable viscous drag and being responsive to said eld being positioned within said container and freely movable in the uid, and means for recording the deflection of said support member caused by movement of the container when -a magnetic field is established.

4. A device for measuring the viscosity of a fluid comprising in combination a substantially non-magnetic container for the fluid mounted on a pivoted, movable support member, a solenoid winding surrounding a medial portion of said container, a solenoid core positioned in and freely movable in the fluid within said container, means for intermittently electrically energizing said Winding whereby said core is caused to move into the resultant magnetic field, and means for recording the deflection of said support member :caused by movement of the container when a magnetic field is established by the electrical energizing of the solenoid winding.

5. VA device according to claim 4 wherein the container is provided with means for heating the container to any predetermined temperature, and with means for recording the temperature of the fluid in the container.

6. A device according to claim 4 in which the container is provided with means for pressurizing the interior and the contents of the container, and With means for recording the pressure within the container.

7. A device for measuring the viscosity of a fluid comprising in combination a substantially non-magnetic container for the fluid mounted on a pivofted, movable support member, a solenoid Winding surrounding a medial portion of said container, a solenoid core positioned and freely movable in the fluid within said container, means for intermittently electrically energizing said winding whereby said core is caused to move into the resultant magnetic field, means for recording the dellection of said support member caused by movement of the container when a magnetic field is established by the electrical energizing of the solenoid winding, and means for adjusting the position of ehe container and its support member with respect to a fixed, predetermined position on said recording means depending upon the density of the fluid placed in the container.

8. A device according to claim 2 wherein the container is supported on an electrical transducer, the latter being provided with means for indicating the varying electrical resistance of the transducer as a result of the movement of the container when the solenoid is energized and the core moves through the fluid into the magnetic eld.

9. A device according to claim 2 wherein the container is supported on -a carbon pile electrical transducer which is provided with electrical means for indicating the varying resistance of the carbon pile resulting from the movement of the container caused by the action of the magnetic eld upon the `core when the solenoid is energized and the core moves through the fluid into the iield.

10. A device for measuring the viscosity of ka fluid whose viscosity changes under different pressure and temperature conditions comprising in combination a substantially non-magnetic container for the fluid, electromagnetic winding means for establishing a magnetic field in a medial portion of a cavity in said container, means having an appreciable viscous drag and being responsive References Cited in the file of this patent UNITED STATES PATENTS Edgecomb July 2, 1918 Clagett Feb. 17, 1942 OTHER REFERENCES Maclnnes, Dayhoff, and Ray, A Magnetic Float Method for Determining the Densities of Solutions, August 1951, published in The Review of Scientific Instruments,

20 volume 22, number 8, pages 642-646.

am.; mi.; 

